Gallium nitride-based III-V nitrides, which receive attention as excellent blue light-emitting devices, are in actual use as materials for light-emitting diodes and semiconductor laser diodes. In a method described in Japanese Patent Publication (Laid-Open) No. 2003-313099A, a group III nitride single crystal is grown using a flux method. That is, a seed crystal is placed in evenly heated flux such that the growth surface is parallel to a gas-liquid interface, thereby to grow a single crystal.
Further, in Japanese Journal of Applied Physics, Vol. 42 (2003), pp. L729-731 by Kawamura et al., a nitride single crystal is grown in a manner that a seed crystal is placed in evenly heated flux such that the growth surface is perpendicular to a gas-liquid interface. In this case, the seed crystal is placed vertically.
Still further, Japanese Patent Publication (Laid-Open) No. 2004-231447A discloses a method for growing a nitride single crystal by providing a considerably large difference in temperature between a gas-liquid interface and a single crystal-growing region. In an example of this document, a temperature difference within a melt is 150° C. or higher.
In addition, in Japanese Patent Publication (Laid-Open) No. 2005-154254A, a temperature difference within a melt is set to 10° C. to 300° C., preferably 100° C. to 200° C.